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#	Question	Answer
1	Who was Alfonso Corti?	Alfonso Corti was an Italian anatomist born in 1822.
2	What did Alfonso Corti initially study in his scientific career?	He studied the cardiovascular systems of reptiles.
3	Which system did Alfonso Corti later focus on?	The mammalian auditory system.
4	What important structure did Alfonso Corti describe in 1851?	The organ of Corti located on the basilar membrane of the cochlea.
5	What is the function of the hair cells in the organ of Corti?	They convert sound vibrations into nerve impulses.
6	What approach resulted in the increasing use of physico-chemical concepts and techniques in biology?	The reductionist approach to the study of life forms.
7	Which field experienced an explosion of knowledge due to reductionist studies?	Molecular biology.
8	Molecular physiology became almost synonymous with which two subjects?	Biochemistry and biophysics.
9	What does systems biology suggest about living phenomena?	Living phenomena are emergent properties due to interactions among system components.
10	Name some levels that create emergent properties according to systems biology.	Molecules, supramolecular assemblies, cells, tissues, organisms, populations, and communities.
11	What is another common term for breathing?	Respiration.
12	On what factors do mechanisms of breathing vary among animals?	Habitats and levels of organisation.
13	How do lower invertebrates like sponges and flatworms exchange gases?	By simple diffusion over their entire body surface.
14	Which respiratory structure is used by earthworms?	Moist cuticle.
15	What respiratory system is present in insects?	A network of tracheal tubes.
16	Which respiratory organs are used by most aquatic arthropods and molluscs?	Gills (branchial respiration).
17	Which respiratory organs are used by terrestrial forms?	Lungs (pulmonary respiration).
18	Which vertebrates respire through gills?	Fishes.
19	Which vertebrates respire through lungs?	Amphibians, reptiles, birds, and mammals.
20	What is cutaneous respiration?	Respiration through moist skin.
21	Which amphibian mentioned in the text performs cutaneous respiration?	Frog.
22	Where are the external nostrils located in humans?	Above the upper lips.
23	Through what does the nasal chamber open into the pharynx?	Nasal passage.
24	Which part of the respiratory tract is a common passage for food and air?	Pharynx.
25	What is the larynx commonly called?	Sound box.
26	Why is the larynx called the sound box?	Because it helps in sound production.
27	What prevents food from entering the larynx during swallowing?	Epiglottis.
28	What is the epiglottis?	A thin elastic cartilaginous flap covering the glottis during swallowing.
29	Into what does the trachea divide at the level of the 5th thoracic vertebra?	Right and left primary bronchi.
30	What are the successive branches formed from bronchi?	Secondary bronchi, tertiary bronchi, and bronchioles.
31	What are alveoli?	Thin, irregular-walled, vascularised bag-like structures formed from terminal bronchioles.
32	Which structures together comprise the lungs?	Bronchi, bronchioles, and alveoli.
33	What covers the lungs externally?	A double-layered pleura.
34	What is present between the two pleural membranes?	Pleural fluid.
35	What is the function of pleural fluid?	It reduces friction on the lung surface.
36	Which pleural membrane is in close contact with the thoracic lining?	Outer pleural membrane.
37	Which pleural membrane is in contact with the lung surface?	Inner pleural membrane.
38	Which part of the respiratory system extends from the external nostrils to the terminal bronchioles?	The conducting part.
39	Which structures form the respiratory or exchange part of the respiratory system?	Alveoli and their ducts.
40	What is the main function of the conducting part of the respiratory system?	It transports atmospheric air to the alveoli.
41	Besides transporting air, what other functions are performed by the conducting part?	Clearing foreign particles, humidifying air, and bringing air to body temperature.
42	In which chamber are the lungs situated?	Thoracic chamber.
43	Why is the thoracic chamber important for breathing?	Changes in thoracic volume are reflected in pulmonary volume.
44	What forms the dorsal boundary of the thoracic chamber?	Vertebral column.
45	What forms the ventral boundary of the thoracic chamber?	Sternum.
46	What forms the lateral boundary of the thoracic chamber?	Ribs.
47	What forms the lower boundary of the thoracic chamber?	Dome-shaped diaphragm.
48	Why is the anatomical setup of lungs in the thorax essential for breathing?	Because pulmonary volume cannot be altered directly.
49	Name the five steps involved in respiration.	Pulmonary ventilation, diffusion of gases across alveolar membrane, transport of gases by blood, diffusion between blood and tissues, and cellular respiration.
50	What are the two stages of breathing?	Inspiration and expiration.
51	What happens during inspiration?	Atmospheric air is drawn into the lungs.
52	What happens during expiration?	Alveolar air is released out.
53	How does air move into and out of the lungs?	By creating a pressure gradient between lungs and atmosphere.
54	Under what condition does inspiration occur?	When intra-pulmonary pressure is less than atmospheric pressure.
55	Under what condition does expiration occur?	When intra-pulmonary pressure is higher than atmospheric pressure.
56	Which muscles help generate pressure gradients during breathing?	Diaphragm and intercostal muscles.
57	What happens during contraction of the diaphragm in inspiration?	Thoracic chamber volume increases in the antero-posterior axis.
58	What is the role of external intercostal muscles during inspiration?	They lift up the ribs and sternum.
59	What happens to thoracic volume during inspiration?	It increases.
60	What effect does increased pulmonary volume have on intra-pulmonary pressure?	It decreases intra-pulmonary pressure below atmospheric pressure.
61	Why does air enter the lungs during inspiration?	Due to lower intra-pulmonary pressure than atmospheric pressure.
62	What occurs when the diaphragm and intercostal muscles relax?	Thoracic and pulmonary volume decrease.
63	What happens to intra-pulmonary pressure during expiration?	It rises slightly above atmospheric pressure.
64	What causes expulsion of air from the lungs?	Increased intra-pulmonary pressure.
65	Which muscles can increase the strength of inspiration and expiration?	Additional muscles in the abdomen.
66	What is the average breathing rate of a healthy human?	12 - 16 times per minute.
67	Which instrument is used to estimate the volume of air involved in breathing movements?	Spirometer.
68	What is the clinical use of a spirometer?	Clinical assessment of pulmonary functions.
69	What is Tidal Volume (TV)?	Volume of air inspired or expired during normal respiration.
70	What is the approximate tidal volume in a healthy human?	Approximately 500 mL.
71	How much air can a healthy man inspire or expire per minute during normal breathing?	Approximately 6000 to 8000 mL.
72	What is Inspiratory Reserve Volume (IRV)?	Volume of air a person can inspire by forcible inspiration.
73	What is the average Inspiratory Reserve Volume?	2500 mL to 3000 mL.
74	What is Expiratory Reserve Volume (ERV)?	Volume of air a person can expire by forcible expiration.
75	What is the average Expiratory Reserve Volume?	1000 mL to 1100 mL.
76	What is Residual Volume (RV)?	Volume of air remaining in the lungs even after a forcible expiration.
77	What is the average Residual Volume (RV) in humans?	1100 mL to 1200 mL.
78	What are pulmonary capacities derived from?	By adding different respiratory volumes.
79	What is the clinical significance of pulmonary capacities?	They are used in clinical diagnosis.
80	What is Inspiratory Capacity (IC)?	Total volume of air a person can inspire after a normal expiration.
81	Which volumes make up Inspiratory Capacity (IC)?	Tidal Volume (TV) + Inspiratory Reserve Volume (IRV).
82	What is Expiratory Capacity (EC)?	Total volume of air a person can expire after a normal inspiration.
83	Which volumes make up Expiratory Capacity (EC)?	Tidal Volume (TV) + Expiratory Reserve Volume (ERV).
84	What is Functional Residual Capacity (FRC)?	Volume of air remaining in the lungs after a normal expiration.
85	Which volumes make up Functional Residual Capacity (FRC)?	ERV + RV.
86	What is Vital Capacity (VC)?	Maximum volume of air a person can breathe in after a forced expiration.
87	Which volumes are included in Vital Capacity (VC)?	ERV + TV + IRV.
88	What is another definition of Vital Capacity (VC)?	Maximum volume of air a person can breathe out after a forced inspiration.
89	What is Total Lung Capacity (TLC)?	Total volume of air accommodated in the lungs at the end of a forced inspiration.
90	Which volumes are included in Total Lung Capacity (TLC)?	RV + ERV + TV + IRV.
91	What is another expression for Total Lung Capacity (TLC)?	Vital Capacity + Residual Volume.
92	What are the primary sites of exchange of gases?	Alveoli.
93	Between which two locations does gas exchange also occur apart from alveoli?	Between blood and tissues.
94	On what factor is diffusion of gases mainly based?	Pressure/concentration gradient.
95	Which additional factors affect the rate of diffusion of gases?	Solubility of gases and thickness of membranes.
96	What is partial pressure?	Pressure contributed by an individual gas in a mixture of gases.
97	What is the partial pressure of oxygen in atmospheric air?	159 mm Hg.
98	In which direction does oxygen diffuse according to concentration gradient?	From alveoli to blood and blood to tissues.
99	In which direction does carbon dioxide diffuse according to concentration gradient?	From tissues to blood and blood to alveoli.
100	Name the three major layers of the diffusion membrane.	Thin squamous epithelium of alveoli, endothelium of alveolar capillaries, and basement substance.
101	What forms the basement substance in the diffusion membrane?	Thin basement membrane supporting squamous epithelium and basement membrane surrounding endothelial cells.
102	What is the thickness of the diffusion membrane?	Much less than a millimetre.
103	What percentage of oxygen is transported by RBCs?	About 97%.
104	What percentage of oxygen is transported dissolved in plasma?	About 3%.
105	What is haemoglobin?	A red coloured iron-containing pigment present in RBCs.
106	What compound is formed when oxygen binds with haemoglobin?	Oxyhaemoglobin.
107	Is the binding of oxygen with haemoglobin reversible or irreversible?	Reversible.
108	Where does oxygen bind to haemoglobin?	At the lung surface.
109	Where does oxygen dissociate from oxyhaemoglobin?	At the tissues.
110	How much oxygen can every 100 mL of oxygenated blood deliver to tissues?	Around 5 mL.
111	Where else besides RBCs is carbonic anhydrase present?	In minute quantities in plasma.
112	Which system regulates respiratory rhythm in humans?	Neural system.
113	Which brain region contains the respiratory rhythm centre?	Medulla region.
114	What is the primary function of the respiratory rhythm centre?	Regulation of respiratory rhythm.
115	Which centre in the brain moderates the respiratory rhythm centre?	Pneumotaxic centre.
116	In which brain region is the pneumotaxic centre located?	Pons region.
117	How does the pneumotaxic centre alter respiratory rate?	By reducing the duration of inspiration.
118	What is the role of oxygen in regulation of respiratory rhythm?	It is quite insignificant.
119	What is asthma?	Difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.
120	What is emphysema?	A chronic disorder in which alveolar walls are damaged, decreasing respiratory surface.
121	What is one major cause of emphysema?	Cigarette smoking.
122	Why do cells utilise oxygen?	For metabolism and production of energy.
123	Why have animals evolved different respiratory mechanisms?	For transport of oxygen to cells and removal of carbon dioxide.
124	What are the main components of the human respiratory system?	Two lungs and associated air passages.
125	What is the first step in respiration?	Breathing.
126	What occurs during inspiration?	Atmospheric air is taken in.
127	What occurs during expiration?	Alveolar air is released out.
128	How are inspiration and expiration carried out?	By creating pressure gradients between atmosphere and alveoli.
129	Which muscles help in breathing movements?	Intercostal muscles and diaphragm.
130	Which instrument estimates volumes of air involved in breathing?	Spirometer.
131	What is the significance of spirometry?	It has clinical significance.
132	By which process do gases exchange at alveoli and tissues?	Diffusion.
133	Which factors affect the rate of diffusion of gases?	Partial pressure gradients, solubility, and thickness of diffusion surface.
134	In which form is oxygen mainly transported in blood?	As oxyhaemoglobin.
135	Which enzyme helps transport carbon dioxide as bicarbonate?	Carbonic anhydrase.
136	What percentage of carbon dioxide is carried as carbamino-haemoglobin?	20 - 25%.
137	Which centre maintains respiratory rhythm?	Respiratory centre in the medulla region of the brain.
138	Which brain centre can alter respiratory mechanism?	Pneumotaxic centre in the pons region.
139	Which area in the medulla can alter respiratory mechanism?	Chemosensitive area.
140	What occupational activities may produce excessive dust leading to respiratory disorders?	Grinding and stone-breaking industries.
141	What happens after long exposure to excessive dust in industries?	Inflammation leading to fibrosis and serious lung damage.
142	What is fibrosis?	Proliferation of fibrous tissues.
143	What protective measure should workers in dusty industries take?	Wear protective masks.
144	What is the definition of vital capacity ?	Maximum volume of air a person can breathe in after forced expiration or breathe out after forced inspiration.
145	Why does diffusion of gases occur mainly in alveolar regions?	Because alveoli are the primary sites of gaseous exchange.
146	What is the site of gaseous exchange in insects?	Tracheal tubes.
147	What is tidal volume?	Volume of air inspired or expired during normal respiration.